JPH0481495B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to fiber reinforced plastics (FRP).
More specifically, the present invention relates to a method for manufacturing a lightweight sandwich cylindrical body, in which the inner and outer skin layers are made of FRP and the core layer is made of sintered foam.

[Conventional technology]

The syntactic foam mentioned above is a material obtained by uniformly dispersing microscopic hollow bodies such as glass or plastic in a resin matrix.Since it is a closed cell, it will not penetrate into the voids unless cracks occur in the resin matrix. It has the following characteristics: no water intrusion, high compressive strength, withstands strong lateral pressure, and low specific gravity.
It fully satisfies the conditions required for a buoyant body.

Therefore, among the sand german structures used for various purposes as lightweight structures, those with synthetic foam as the core material are suitable for use as deep-sea structures or, due to their high reliability, as primary structural materials for aircraft. Applications are being planned.

Conventionally, such cylindrical structures are formed by forming an inner skin, generally by the FW (filament winding) method, and then adhering a core layer of pre-formed sintered foam thereon.
They are manufactured by forming an outer skin thereon or by inserting and adhering a pre-formed outer skin, but this conventional method has the following drawbacks.

[Problem that the invention seeks to solve]

That is, since the syntactic foam must be formed in advance, the number of manufacturing steps increases.

Furthermore, the diameters of the molded foam and the skin layer do not match, and the outer periphery must be machined in each step.

Furthermore, since an adhesion process is involved, the number of man-hours is further increased, and there are also reliability problems such as cracks in the foam mainly due to large thermal residual tensile stress generated in the adhesive layer.

Therefore, the present invention aims to eliminate these problems found in the conventional method.

[Means for solving problems]

The manufacturing method of the FRP sandwich cylinder body of the present invention, which achieves the above object, involves preparing in advance two fiber-reinforced plastic cylinder bodies with different diameters, which will serve as the inner and outer skin layers, and then arranging them concentrically. death,
Furthermore, after installing end plates at both ends and filling the void created between the end plate and the inner and outer cylindrical bodies with microballoons, the pressure in the void is reduced through the suction port provided on the end plate. , forming a core layer of the syntactic foam by impregnating and curing the resin matrix through an injection port provided in the other end plate, and integrating this core layer with inner and outer skin layers arranged concentrically. Consists of.

According to this method, the molding of the syntactic foam core and the adhesion to the skin layer can be performed simultaneously.

Furthermore, since the core layer is molded between the skin layers as inner and outer molds, machining of each layer is not required.

In addition, the inner and outer molds can be centered with high accuracy using the end plates, and thermal residual stress is alleviated by using the core matrix resin as an adhesive, resulting in highly accurate and highly reliable products. can get.

〔Example〕

An example of the method of the present invention will be explained based on the accompanying drawings.

As shown in FIG. 1, cylindrical bodies 1 and 2 made of FRP with different diameters are manufactured in advance and arranged on concentric circles. Furthermore, end plates 3 and 4 are provided at both ends of the cylindrical bodies 1 and 2, which have the function of holding them concentrically and the function of airtightly sealing the gap between the cylindrical bodies 1 and 2. The upper end plate 3 has a vacuum outlet 5, and on the other hand,
The lower end plate 4 is provided with a resin injection port 8 whose one end is immersed into the resin 7 placed in the tank 6.

After that, the cavity defined by the cylindrical bodies 1 and 2 and the end plates 3 and 4 is filled with the micro hollow bodies 9.
A filter paper 10 such as glass cloth is interposed to hold the hollow body 9 at the upper and lower ends of the gap and to uniformly inject the resin into the gap in the circumferential direction.

Next, after filling the cavity with the hollow body and attaching the end plates 3 and 4, when vacuum is drawn from the vacuum outlet 5 in this state, the resin 7 in the tank 6 is sucked out from below the cavity. It is successively impregnated into the gaps between the hollow bodies and finally flows out from the vacuum outlet 5.

Therefore, the vacuum is stopped and the impregnated resin is cured by heating or at room temperature to form a syntactic foam, and at the same time, it is bonded and integrated with the cylindrical bodies 1 and 2 used as the inner and outer molds.

After going through the above steps, the core 1 of the sanderch cylindrical body shown in FIG.
A cylindrical body 14 in which 3 is sandwiched between FRP skin layers 11 and 12 is completed.

Incidentally, when impregnating the resin 7, the injection time can be shortened by sealing the tank 6 and applying pressure for pumping the resin inside with nitrogen gas or the like to further increase the pressure difference for resin impregnation.

Further, considering the impregnating property of the resin, it is preferable that the impregnating viscosity of the resin matrix is 20 poise or less.

Furthermore, considering pressure resistance and solubility in resin, glass microballoons are preferable to microballoons made of resin.

〔effect〕

According to the method of the present invention explained above, a core layer is formed between the two skin layers prepared in advance by using them as inner and outer molds, and at the same time, the core layer is integrated with the skin layer, so that the synthetic foam core is There is no need for a preforming process, gluing process, or machining process for diameter adjustment, and a significant reduction in man-hours can be expected.

In addition, because the skin layers, which serve as the inner and outer molds, can be centered using the end plates, there is less uneven thickness.Furthermore, since there is no adhesive layer between the core and skin layer, which existed in the past, there is no possibility of cracks in the core due to thermal residual stress. Therefore, highly reliable products can be provided.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an example of the method of the present invention, and FIG. 2 is a sectional view of a sanderch cylindrical body obtained by the method. 1, 2...FRP cylindrical body, 3, 4...end plate, 5
... Vacuum inlet, 6 ... Tank, 7 ... Resin, 8 ... Resin injection port, 9 ... Micro hollow body, 10 ... Filter paper, 1
1, 12... skin layer, 13... core, 14...
Sanderutsch cylindrical body.

Claims (1)

[Claims] 1 Two fiber-reinforced plastic cylindrical bodies with different diameters, which serve as the inner and outer skin layers, are produced in advance and arranged on a concentric circle, and end plates are provided at both ends. After filling the gap created between the end plate and the inner and outer cylindrical bodies with microballoons, the gap is depressurized through the suction port provided on one end plate, and then the injection port provided on the other end plate is removed. A fiber-reinforced plastic made by impregnating and curing a resin matrix to form a core layer of syntactic foam, and integrating this core layer with inner and outer skin layers arranged concentrically. Method for manufacturing a sanderch cylinder. 2. Claim 1, characterized in that the resin matrix has an impregnation viscosity of 20 poise or less.
A method for producing a sandwich cylinder made of fiber-reinforced plastics as described in 2. 3. The method for manufacturing a fiber-reinforced plastic sandwich cylinder according to claim 1 or 2, wherein the microballoon is a glass micro hollow body. 4. The method for manufacturing a fiber-reinforced plastic sanderch cylindrical body according to any one of claims 1 to 3, characterized in that a pumping pressure is applied to the resin during impregnation with the resin matrix.